96 Sport 1100 gas tank pressure issues

[code]

I have a 96 Sport 1100. When it gets hot out or my bike is in the sun the tank pressurizes and forces fuel out through the carbs. It pours out pretty good. If I wiggle the gas cap it releases out a lot of pressure. Any ideas as to why? And how to fix this?

[docc]

Hey, Code, go to your profile and enter your location. You don't have to be very specific. Even a country will help other members know what sort of fitment your bike might have.

 

Under your gas cap, there may be a little hole to vent the tank into a tube. I recall that is a steel tank and not like mine, but check for a vent tube and be sure it is not kinked or clogged.

[code]

Location added. I checked the tube your talking about, its not kinked but it is attached to the to a fitting on the bottom of the tank. So it doesnt vent the tank at all. From what I was told that was so any fluids caught in that ring on top of the tank could drain through that line and out of the bottom of the bike. I was told that the gas cap is supposed to vent, anybody know if this is true?

[jcbooghs]

It helps when you don't pour your gastank too full. Stay a bit under the collar in the tank when you fill. All the Sports (and Daytona's) from that time, with that specific cap have it. You will notice your cap turning yellowish from fuel gasses, so I think it is vented, a little bit. I once tried another kind of rubber in the cap to stop the cap turning yellow. When I moved the cap a little there was a big 'Whoooosh' indicating there was a huge pressure inside. I don't know if there is a solution, maybe another gascap? Or add an extra venting hole with hose.

[GuzziMoto]

In the USA it is common practice to have a one way valve in the vent for the gas tank (possibly that fitting you mentioned) that only lets air in to replace the fuel as it is used. It does not allow vapors to escape. But it can cause pressure issues to develop and sometimes it is best to remove the valve.

If the vent is through the cap then it is harder to remove the valve.

[code]

Thanks for the replys everyone. I think I may try to T off the hose from the cap to bottom of the tank and add a vent tube. Id like to solve this before it gets hot again so I dont get stranded somewhere.

[Orange Guzzi]

Thanks for the replys everyone. I think I may try to T off the hose from the cap to bottom of the tank and add a vent tube. Id like to solve this before it gets hot again so I dont get stranded somewhere.

 

Putting a T in the hose will not help. The hose drains the filler neck bung tThe problem per the previous post is the rubber one way plug in the cap. It allows air in and will not release pressure.

 

Just got back from the spine raid and have fueling problems. One of my thought is that the pressure from the fuel tank is causing the left carb to flood. I am going to remove the small black plug from my cap and see if that helps.

[Josh]

Code,

My tank builds pressure too but it dosen't seem to cause a problem.

 

If your problem (flooding carbs) is accuring while parked, it's possible you have a petcock issue.

I would think a properly functioning petcock would withstand these pressures.

Another possibility is twisting the throttle while the bike is at rest. The enrichers (accelerator pumps) on the carb's are dispensing fuel every time the throttle is turned. I found my friends kid doing this to my bike. It took me a while to figure out why my garage had such a strong odor of petrol.

 

Orange,

Good to meet you at the spine raid.

 

You probably already know about this but... here is a pretty handy guide when trying to sort out these lovely Dellorto carburetors.

Note: the float level specifcation and adjustment.

http://www.ducatimeccanica.com/dellorto_guide/dellorto.html

[Orange Guzzi]

When I got around to working on my bike this past week, I found the fuel line was almost blown off the right pet cock. That is with a spring type hose clamp. I removed the rubber vacuum plug from the gas cap and took the bike out for a few rides since. The bike runs much better and consistantly now. I stopped a removed the fuel cap after riding the bike several miles. The fuel tank was not pressurizing.

 

I just can't stay off the bike. I have three bikes and two are being neglected. Getting the bike sorted out over the last couple of weeks has greatly increased the fun factor.